fiddlecollector

If you read my post on page three ,i explained that i had actually bought or was sent the wrong stuff and didnt notice! The correct stuff should be N-acetyl D Glucosamine NOT what i used. I cant explain why the stuff i bought worked but it did . This is the stuff you should be using: https://www.amazon.com.au/BulkSupplements-N-Acetyl-D-Glucosamine-Digestive-Support/dp/B074JGXVNX

Some think an angl e of around 30 degrees is ideal but going in the opposite direction for a cello bow ,as the down pressure is then more or less perpendicular to the strings when the bow is tilted. My biggest reason is to do with possible crack formation. If the rings are running vertical through the head stick from top to bottom and a crack develops its far more of a problem than when the rings are parallel or at a shallow angle to the strings .. I `ve seen numerous old bows with hair line racks running vertically through the stick ,that have held for decades or even probably since shortly after being made that are perfectly stable in regards to using as a playing tool. Ive also seen many with rings going vertical to the strings that have lost their head (particularly just across the head stick transition point. Remember that cracks develop usually perpendicular to the ring direction.

They are appear to be bows from China and sold through French and Tunisian shops. The company was supposed to be established in 1972.

When your talking about bows ,slab cut versus quarter or whatever ! it depends which way your describing the cut . A bow is generaly more like a violin neck ( not like a violin top or back) but usually off by up to 30 degrees either side. When you talk of a quarter cut neck on guitars the quarter sawn types are usually opposite to a violin neck. So quarter sawn could mean anything depending on what direction your viewing from.

Thats assuming the particular violin had been anywhere near Hills. Hill cases like that are not exactly rare ive had loads of them over the years ..

It should yes ,improves with heating the joint . Also water resistance improves. Heres a graph/chart showing efect on water reistance after 90 days in water. It shows straight gelatin/glue, sucrose (common white table sugar), glucose, glucosamine and finally the best N-Acetyl-D Glucosamine. So sort of disproves slightly the idea that adding sugar attracts moisture.Dont know if honey works but probably soewhere between glucose and sucrose.. Notice though that N-Acetyl-D Glucosamine has a huge effect compared to other sugars. Heres a similar one for effect on tensile stress.

I have realised that i dont know how this stuff works ,just that it does . I have found excerpts from one of the articles i read and realised i bought the wrong stuff(N-Acetyl -L Glutamine). Unless Amazon sent me the wrong stuff because they sound similar and i didnt realise Considering im a former chemist im quite embarassed . I will still use it. But will also try the correct stuff which is N-acetyl-D Glucosamine. The proper stuff N-Acetyl -D Glucosamine which is a sugar complex, apparently works partly by the Maillard reaction crosslinking with the gelatin. Also the longer you can keep the joint at an elevated temperature the stronger the joint. The tensile strength of the modified glue can increase to up to 170 - 200+MPa. Whereas unmodified hide glue is a maximum of around 40 - 70 MPa. So that a huge increase. So creep using N-acetyl-D Glucosamine modified hide glue ,would be likely less.Just guessing here . A few other things, some use glutaraldehyde instead of formaldehyde for cross linking. Apparently this only has a surface effect on gelatin ,so it will not be as water reistant as when using N-Acetyl-D Glucosamine. Most types of sugars such as sucrose ,glucose,etc... also crosslink gelatin. Heating of the joints of over 50 centigrade for a few hours increases tensile strength and water resistance- this applies to all sugar types .

Hope its useful, i certainly use it for bow frogs. I forgot to mention that the joint is best heated to around 50 - 60 centigrade for a short time as its supposed to increase and speed up the initial cross linking. Its certainly better than nasty formaldehyde .

I came across a mention on an old scientific paper ,which was testing crosslinking agents for proteins, i dont think it was anything to do with wood glues though ,more medical. There doesnt appear to be any difference in the visability of the glue line

I may have mentioned a few months back an alternative to formaldehyde for treating hide glue for bow frog repairs etc.... Well i did various tests and im impressed and have used it since. The alternative is called N-acetyl- L glutamine, in powder form often used by health freak/body builder types and i bought 100gms of pure powder of amazon for around £7,which will last me years. I did various tests on pieces of ebony and all were successful as far as im concerned. You add 2-5% of the powder to the dry weight of the hide glue.Then make the glue as usual. Heres a couple of tests , One is treating the hide glue, drying it out on a plastic film then submerging in warm water for a week.The edges o this piece of glue were paper thin like cling film. The second is spliting a scrap piece of ebony and gluing it . The ebony was straight grained and split down the middle almost exactly so i had two almost identical halves.Once dried for a few days this was also submerged in the same jar of warm water for a week. The piece of glue didnt dissolve but did swell slightly ,but all the thin edges are still intact. The dark colour is stain from the ebony out of the water. The block of ebony ,i couldnt snap it with my hand pressure. I stuck it in a vice and hit it three times with a hammer and it broke but interestingly and importantly in didnt break along the entire glue line ,it sort of started at it and wandered off into wood . So the bond was stronger than the wood after one week soaking in hot water. I think this is a good result and the powder is edible unlike the toxic formaldehyde. Some photos showing the piece of glue before and after soaking as well as the block with the glue line indicated.

More like a maximum of 76.5%. It has between 40-70% Dimethylmethoxyphenyl siloxane as the main ingredient plus two other organo- silicone compounds, as well as several other ingredients. I dont know much about silicone compounds like this so maybe there are types that set hard and they are not quite like bathroom sealant. Think i`ll buy some just to see what it does! Can`t stand the forming PU type.

Interesting , is it not rubbery ?? I can understand good water resistance as its similar to the stuff bathroom silicone sealants are made from.

Which glue are we talking about, gorilla glue was initially a moisture activated polyurethane glue. The Gorilla clear glue is complately different and based on silicone.. They also make superglue etc.... ??????

Thats around 2 % which is pretty normal for insurance provided by shippers. Have you thought about something like this ,they charge 0.6% of the item value and cover most standard shipping methods. They are based in Paris but cover the US and Taiwan i think . I have no experience with them but they are certainly cheaper. https://www.secursus.com/

The little pin knot on the op`s bow is relatively harmless . The ones which cause the problems are when you see all the grain around the knot deflecting in all directions . Hard to describe in words.